#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
#define fastio ios::sync_with_stdio(false), cin.tie(0)
#pragma GCC optimize("Ofast")
#define pb push_back
#define eb emplace_back
#define f first
#define s second
#define lowbit(x) x&-x
const int maxn = 2e5 + 5;
int to[maxn];
int indeg[maxn];
map<string, int> mp;
int cnt = 0;
signed main(void){
fastio;
int n;
cin>>n;
int ans = 0;
for(int i = 0; i < n; i++){
string a, b;
cin>>a>>b;
int id1 = (mp[a] ? mp[a] : mp[a] = ++cnt), id2 = (mp[b] ? mp[b] : mp[b] = ++cnt);
to[id1] = id2;
indeg[id2] ++;
}
if(n % 2){
cout<<-1<<"\n";
return 0;
}
vector<int> formed(n + 1);
for(int i = 1; i <= n; i++){
if(formed[i]) continue;
if(to[i] != i && to[to[i]] == i){
formed[i] = formed[to[i]] = 1;
}
}
queue<int> q;
for(int i = 1; i <= n; i++){
if(!indeg[i]) q.push(i);
}
int left = 0;
while(!q.empty()){
int pos = q.front(); q.pop();
if(formed[to[pos]]){
left++;
continue;
}
ans++;
indeg[to[to[pos]]] --;
if(!formed[to[to[pos]]] && !indeg[to[to[pos]]]) q.push(to[to[pos]]);
formed[pos] = formed[to[pos]] = 1;
}
vector<int> vis(n + 1);
for(int i = 1; i <= n; i++){
if(!formed[i] && indeg[i] && !vis[i]){
int tmp = to[i], len = 1;
vis[i] = 1;
while(tmp != i){
vis[tmp] = 1, len++, tmp = to[tmp];
}
ans += len / 2, left += len % 2;
}
}
cout<<ans + left<<"\n";
}
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
348 KB |
Output is correct |
2 |
Correct |
0 ms |
348 KB |
Output is correct |
3 |
Correct |
0 ms |
348 KB |
Output is correct |
4 |
Correct |
0 ms |
348 KB |
Output is correct |
5 |
Correct |
1 ms |
348 KB |
Output is correct |
6 |
Correct |
0 ms |
348 KB |
Output is correct |
7 |
Correct |
0 ms |
348 KB |
Output is correct |
8 |
Correct |
0 ms |
348 KB |
Output is correct |
9 |
Correct |
0 ms |
348 KB |
Output is correct |
10 |
Correct |
0 ms |
348 KB |
Output is correct |
11 |
Correct |
0 ms |
348 KB |
Output is correct |
12 |
Correct |
0 ms |
348 KB |
Output is correct |
13 |
Correct |
0 ms |
348 KB |
Output is correct |
14 |
Correct |
0 ms |
348 KB |
Output is correct |
15 |
Correct |
0 ms |
348 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
348 KB |
Output is correct |
2 |
Correct |
0 ms |
348 KB |
Output is correct |
3 |
Correct |
0 ms |
348 KB |
Output is correct |
4 |
Correct |
115 ms |
11860 KB |
Output is correct |
5 |
Correct |
122 ms |
11860 KB |
Output is correct |
6 |
Correct |
113 ms |
11864 KB |
Output is correct |
7 |
Correct |
112 ms |
11204 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
116 ms |
11860 KB |
Output is correct |
2 |
Correct |
118 ms |
11908 KB |
Output is correct |
3 |
Correct |
99 ms |
11860 KB |
Output is correct |
4 |
Correct |
109 ms |
11096 KB |
Output is correct |
5 |
Correct |
111 ms |
11856 KB |
Output is correct |
6 |
Correct |
111 ms |
12116 KB |
Output is correct |
7 |
Correct |
112 ms |
12080 KB |
Output is correct |
8 |
Correct |
108 ms |
12000 KB |
Output is correct |
9 |
Correct |
104 ms |
12112 KB |
Output is correct |
10 |
Correct |
81 ms |
11960 KB |
Output is correct |
11 |
Correct |
1 ms |
344 KB |
Output is correct |
12 |
Correct |
0 ms |
344 KB |
Output is correct |
13 |
Correct |
1 ms |
348 KB |
Output is correct |
14 |
Correct |
1 ms |
344 KB |
Output is correct |
# |
결과 |
실행 시간 |
메모리 |
Grader output |
1 |
Correct |
0 ms |
348 KB |
Output is correct |
2 |
Correct |
0 ms |
348 KB |
Output is correct |
3 |
Correct |
0 ms |
348 KB |
Output is correct |
4 |
Correct |
0 ms |
348 KB |
Output is correct |
5 |
Correct |
1 ms |
348 KB |
Output is correct |
6 |
Correct |
0 ms |
348 KB |
Output is correct |
7 |
Correct |
0 ms |
348 KB |
Output is correct |
8 |
Correct |
0 ms |
348 KB |
Output is correct |
9 |
Correct |
0 ms |
348 KB |
Output is correct |
10 |
Correct |
0 ms |
348 KB |
Output is correct |
11 |
Correct |
0 ms |
348 KB |
Output is correct |
12 |
Correct |
0 ms |
348 KB |
Output is correct |
13 |
Correct |
0 ms |
348 KB |
Output is correct |
14 |
Correct |
0 ms |
348 KB |
Output is correct |
15 |
Correct |
0 ms |
348 KB |
Output is correct |
16 |
Correct |
0 ms |
348 KB |
Output is correct |
17 |
Correct |
0 ms |
348 KB |
Output is correct |
18 |
Correct |
0 ms |
348 KB |
Output is correct |
19 |
Correct |
115 ms |
11860 KB |
Output is correct |
20 |
Correct |
122 ms |
11860 KB |
Output is correct |
21 |
Correct |
113 ms |
11864 KB |
Output is correct |
22 |
Correct |
112 ms |
11204 KB |
Output is correct |
23 |
Correct |
116 ms |
11860 KB |
Output is correct |
24 |
Correct |
118 ms |
11908 KB |
Output is correct |
25 |
Correct |
99 ms |
11860 KB |
Output is correct |
26 |
Correct |
109 ms |
11096 KB |
Output is correct |
27 |
Correct |
111 ms |
11856 KB |
Output is correct |
28 |
Correct |
111 ms |
12116 KB |
Output is correct |
29 |
Correct |
112 ms |
12080 KB |
Output is correct |
30 |
Correct |
108 ms |
12000 KB |
Output is correct |
31 |
Correct |
104 ms |
12112 KB |
Output is correct |
32 |
Correct |
81 ms |
11960 KB |
Output is correct |
33 |
Correct |
1 ms |
344 KB |
Output is correct |
34 |
Correct |
0 ms |
344 KB |
Output is correct |
35 |
Correct |
1 ms |
348 KB |
Output is correct |
36 |
Correct |
1 ms |
344 KB |
Output is correct |
37 |
Correct |
119 ms |
11856 KB |
Output is correct |
38 |
Correct |
112 ms |
12180 KB |
Output is correct |
39 |
Correct |
126 ms |
12344 KB |
Output is correct |
40 |
Correct |
111 ms |
12112 KB |
Output is correct |
41 |
Correct |
112 ms |
12012 KB |
Output is correct |
42 |
Correct |
111 ms |
11972 KB |
Output is correct |
43 |
Correct |
126 ms |
11936 KB |
Output is correct |
44 |
Correct |
112 ms |
11944 KB |
Output is correct |
45 |
Correct |
111 ms |
12116 KB |
Output is correct |
46 |
Correct |
112 ms |
12116 KB |
Output is correct |
47 |
Correct |
107 ms |
12236 KB |
Output is correct |
48 |
Correct |
124 ms |
11860 KB |
Output is correct |
49 |
Correct |
113 ms |
11860 KB |
Output is correct |
50 |
Correct |
100 ms |
11856 KB |
Output is correct |
51 |
Correct |
109 ms |
10976 KB |
Output is correct |
52 |
Correct |
118 ms |
11884 KB |
Output is correct |
53 |
Correct |
113 ms |
12072 KB |
Output is correct |
54 |
Correct |
112 ms |
12148 KB |
Output is correct |
55 |
Correct |
109 ms |
12116 KB |
Output is correct |
56 |
Correct |
106 ms |
12168 KB |
Output is correct |
57 |
Correct |
83 ms |
12012 KB |
Output is correct |
58 |
Correct |
0 ms |
348 KB |
Output is correct |
59 |
Correct |
0 ms |
464 KB |
Output is correct |
60 |
Correct |
0 ms |
348 KB |
Output is correct |
61 |
Correct |
0 ms |
348 KB |
Output is correct |
62 |
Correct |
0 ms |
348 KB |
Output is correct |
63 |
Correct |
0 ms |
348 KB |
Output is correct |
64 |
Correct |
0 ms |
348 KB |
Output is correct |
65 |
Correct |
118 ms |
11860 KB |
Output is correct |
66 |
Correct |
115 ms |
11840 KB |
Output is correct |
67 |
Correct |
113 ms |
11884 KB |
Output is correct |
68 |
Correct |
110 ms |
11092 KB |
Output is correct |
69 |
Correct |
0 ms |
348 KB |
Output is correct |
70 |
Correct |
0 ms |
348 KB |
Output is correct |
71 |
Correct |
1 ms |
348 KB |
Output is correct |
72 |
Correct |
1 ms |
348 KB |
Output is correct |
73 |
Correct |
0 ms |
348 KB |
Output is correct |
74 |
Correct |
0 ms |
348 KB |
Output is correct |
75 |
Correct |
0 ms |
348 KB |
Output is correct |
76 |
Correct |
0 ms |
348 KB |
Output is correct |
77 |
Correct |
0 ms |
348 KB |
Output is correct |
78 |
Correct |
0 ms |
348 KB |
Output is correct |
79 |
Correct |
0 ms |
348 KB |
Output is correct |
80 |
Correct |
0 ms |
348 KB |
Output is correct |
81 |
Correct |
1 ms |
348 KB |
Output is correct |
82 |
Correct |
0 ms |
348 KB |
Output is correct |
83 |
Correct |
0 ms |
348 KB |
Output is correct |